Field of the Invention
This invention relates, in general, to combustion heating appliances having a heater plug and, in particular, to a new and useful heater plug for heating appliances which has a furnace with a wall having a cooling air passage which is connectable to a combustion air inlet for the heater plug through a throttling device.
The invention concerns a heater plug, cooled with combustion air, for diesel oil-operated heating appliances, especially such as are provided with a vaporizing burner; the heater plug is screwed into a burner pipe joint, enclosing it at distance, which supplies the fuel and is secured to the furnace wall of the heating appliance.
In such heater plugs, when using low quality, i.e., late boiling fuels, or when the combustion air is polluted by a dustladen environment, or when the coke deposit is improperly stripped off during the previous changing of the plug, the plug aeration channel may be gradually worn down at especially vulnerable locations. This impairs the cooling action. The plug becomes too hot and is prematurely consumed.